Chinese hamster ovary (CHO) cells are the most commonly used mammalian cell line for production of biopharmaceutical proteins. Generation of hyperproductive CHO cell lines likely involves the coordinated re-programming of multiple metabolic, secretory, and signaling pathways. To enhance recombinant protein production, such as biopharmaceuticals, in mammalian host cell lines, several strategies are currently employed including optimization of expression vectors and gene amplification methods, media composition and cell culture processes, and cell line engineering to alter apoptosis, growth rates, and metabolic pathways.
Gene silencing using RNA interference (RNAi) technology is a recent approach to alter signaling and metabolic pathways in CHO cells. CHO cell lines with improved viability, enhanced recombinant protein expression and stability, and increased efficacy of monoclonal antibodies were recently generated using RNAi technology. The recent development of genome-scale technologies permits direct cell engineering by manipulating single genes that play important roles in metabolic or regulatory pathways to generate high-producing cell lines. For example, during methotrexate (MTX)-amplification of CHO cells expressing human secreted alkaline phosphatase (SEAP), expression of the actin binding protein cofilin was found to decrease nearly 10-fold as specific SEAP productivity increased.
There remains a need for host cells, especially CHO cells, to be engineered to produce recombinant biopharmaceutical proteins at high levels.